Selected category: Arctic & Antarctic

One of the biggest fears about climate change is that it may be triggering events that would dramatically alter Earth as we know it.

Known to scientists as “tipping events,” they could contribute to mass extinction of species, dramatic sea level rise, extensive droughts and the transformation of forests into vast grasslands – among other upheavals our stressed world can ill afford.

Here are the top six climate events scientists worry about today.

1. The Arctic sea ice melts

The melting of the Arctic summer ice is considered to be the single greatest threat, and some scientists think we’ve already passed the tipping point.

As sea ice melts and the Arctic warms, dark ocean water is exposed that absorbs more sunlight, thus reinforcing the warming. The transition to an ice-free Arctic summer can occur rapidly – within decades – and this has geopolitical implications, in addition to a whole ecosystem being disrupted.

Photo: Smudge 900)

2. Greenland becomes ice-free

The warming of the Arctic may also render Greenland largely ice-free. While Greenland’s ice loss will likely reach the point of no return within this century, the full transition will take at least a few hundred years.

The impacts of the Greenland ice melt is expected to raise sea levels by up to 20 feet.

Half of the 10 largest cities in the world, including New York City, and one-third of the world’s 30 largest cities are already threatened by this sea level rise. Today, they are home to nearly 1.8 billion people.

Other vulnerable American cities include Miami, Norfolk and Boston.

Photo: siralbertus

3. The West Antarctic ice sheet disintegrates

On the other side of Earth, the West Antarctic ice sheet is also disintegrating. Because the bottom of this glacier is grounded below sea level, it’s vulnerable to rapid break-up, thinning and retreat as warm ocean waters eat away at the ice.

Scientists expect the West Antarctic ice sheet to “tip” this century, and there is evidence that it already began happening in 2014.

However, the entire collapse of the glacier, which would raise sea level by 16 feet, could take a few hundred years.

Photo: BBC World Service

4. El Niño becomes a more permanent climate fixture

The oceans absorb about 90 percent of the extra heat that is being trapped in the Earth system by greenhouse gases. This could affect the ocean dynamics that control El Niño events.

While there are several theories about what could happen in the future, the most likely consequence of ocean heat uptake is that El Niño, a natural climate phenomenon, could become a more permanent part of our climate system.

That would cause extensive drought conditions in Southeast Asia and elsewhere, while some drought-prone areas such as California would get relief.

The transition is expected to be gradual and take around a century to occur – but it could also be triggered sooner.

Photo: Austin Yoder

5. The Amazon rain forest dies back

Rainfall in the Amazon is threatened by deforestation, a longer dry season, and rising summer temperatures.

At least half of the Amazon rainforest could turn into savannah and grassland, which – once triggered – could happen over just a few decades. This would make it very difficult for the rainforest to reestablish itself and lead to a considerable loss in biodiversity.

However, the reduction of the Amazon ultimately depends on what happens with El Niño, along with future land-use changes from human activities.

Photo: World Bank

6. Boreal forests are cut in half

Increased water and heat stress are taking a toll on the large forests in Canada, Russia and other parts of the uppermost Northern Hemisphere. So are forest disease and fires.

This could lead to a 50-percent reduction of the boreal forests, and mean they may never be able to recover. Instead, the forest would gradually transition into open woodlands or grasslands over several decades.

This would have a huge impact on the world’s carbon balance because forests can absorb much more carbon than grasslands do. As the forest diminishes, the climate will be affected as will the Earth’s energy balance.

However, the complex interaction between tree physiology, permafrost and fires makes the situation tricky to understand.

Photo: Gord McKenna

Other concerns…

As if that’s not enough, there are a few other tipping events that scientists are also concerned about, but they are even more complex and harder to predict. Examples of such events include the greening of the Sahara and Sahel, the development of an Arctic ozone hole and a chaotic Indian summer monsoon.

How do we keep from tipping over?

We know from measurements that the Earth has had many climate-related tipping events throughout its history. Today’s situation is different, because humans are now driving these changes and the warming is occurring at a faster rate.

But as humans we also have the power to change the trajectory we’re on – possibly in a matter of a few years. We think we know how.

As 2014 draws to a close, two recent developments show that global temperatures are rising at an alarming rate. The world, it seems, is on a run-away train – and yet, we have more reason to feel hopeful than we did a year ago.

I’ll explain why that is. But first, let’s have a look at where we are right now.

West Antarctica ice sheet loss is accelerating

The latest science shows that ice loss from West Antarctica has beenincreasingnearly three times faster in the past decade than during the previous one – and much quicker than scientists predicted.

This unprecedented ice loss isfoundto be occurring because warm ocean water is rising from below and melting the base of the glaciers, dumping huge volumes of additional water – the equivalent of a Mount Everest every two years – into the ocean.

If welost the entireWest Antarctic ice sheet, global sea level would rise 11 feet, threatening nearly 13 million people worldwide and affecting more than $2 trillion worth of property.

2014 may be warmest year on record

The World Meteorological Organizationannouncedrecently that 2014 is on track to be one of the hottest – if not the hottest – year on record.

Continued emissions of heat-trapping gases from energy use, land use, industry, and waste activities contribute to these rising global temperatures.

But there's hope

At Environmental Defense Fund, we spent a year talking to experts from academia, industry, and the activist community to understand what needs and can be done to address climate change.

We analyzed the scientific, economic and political landscapes, and we see that it's possible to reverse the relentless rise of global greenhouse gas emissions within the next five years. But only if countries devote sufficient attention to the task.

What may surprise you is that this can be done with current technology, and at a reasonable cost.

There are two critical components of such a strategy.

One: A few countries can make big progress.

China, the United States, and Europe account for more than half of all global emissions of carbon dioxide from energy use.

The European Union already has an emission reduction plan in place, the U.S. is taking action on carbon pollution from cars and power plants, and China recently reached ahistoric agreementwith the United States to limit emissions.

If we cut emissions of short-lived pollutants such asmethane, which only last in the atmosphere for at most a couple of decades, we can take a sizeable bite out of warming in the near-term.

Methane contributes to around a quarter of the warming we are experiencing today, so this is an enormous opportunity we cannot pass up.

We already have the technology in hand to reduce methane emissions from the oil and gas industry in a cost-effective way. Industry would spend just a penny more for each thousand cubic feet of gas it produces.

It’s not too late

While turning the corner on global emissions by 2020 is feasible, it can only happen with many partners working together.

EDF expects to take actions in alliance with many others that contribute to about half of the needed reductions in short-lived and long-lived emissions we've identified in our five-year strategy. We're also working to set the stage for actions post-2020 that will drive down emissions even further.

While some of the climate change consequences may be irreversible – as appears to be the case with West Antarctica – we can still set ourselves on a much better path for the future by taking action now.

The National Climate Assessment (NCA) report, prepared by the U.S. Global Change Research Program, is essentially the U.S. equivalent of the Intergovernmental Panel on Climate Change (IPCC): Using the best available science, over 300 experts synthesized current understanding of observed and future climate changes and impacts, particularly in the U.S. The third ever NCA was released today, and concludes beyond a reasonable scientific doubt that Americans are being affected by climate change.

Among the findings:

U.S. average temperatures have increased by 1.3 to 1.9ºF since record-keeping began in 1895, and most of this warming has occurred since 1970

Heavy precipitation has increased in many parts of the country

Extremes such as heat waves, droughts, floods, and North Atlantic hurricanes are more frequent and/or intense

Summer sea ice in the Arctic has halved since record-keeping began in 1979

Sea level rise has increased coastal erosion and storm surge damage

These changing conditions produce a variety of tangible stresses on society by affecting human health, water resources, agriculture, energy, infrastructure, and natural ecosystems. The particular impacts vary by region, but no corner of the country is immune to the change.

So what’s happening where you live?

Source: National Climate Assessment

Unless we take immediate action to curb our emissions of heat-trapping gases, the foreseeable future will be plagued by further warming and worsening impacts. The good news is that because we know what the cause is, we also know what is needed in order to stabilize our planet. We must come together now—locally, nationally, and internationally—and work towards a better future.

In the summer of 2012 alone, sea ice shrunk by 350,000 square miles compared to the previous summer. That’s an area the size of Venezuela.

Permafrost, defined as frozen soil, sediment, or rock that has remained at or below zero degrees Celsius for at least two years, comprises about 25 percent of the land in the Northern Hemisphere.Along with record ice melt, all of the permafrost-monitoring sites in northern Alaska have experienced record high temperatures in the past few years.

According to estimates, the carbon dioxide and methane stored in the Northern Hemisphere’s permafrost is equivalent to more than double the carbon concentration currently in the atmosphere.

The Northern Hemisphere’s shallow (zero to three meters deep) permafrost is the part most susceptible to melting, and that part alone contains carbon dioxide and methane equivalent to more than 400 ppm of atmospheric carbon dioxide – or, the amount currently in the entireatmosphere. (That’s according to “Report from International Permafrost Association: Carbon Pools in Permafrost Regions” by Kuhry, Peter, Chien-Lu Ping, Edward A. G. Schuur, Charles Tarnocai, and Sergey Zimov.)

Quick math with very conservative assumptions tells us this: if not curtailed, carbon emissions from the Northern Hemisphere’s permafrost melting will bring the atmospheric carbon concentration beyond 450 ppm, the number the IPCC deems the threshold beyond which the world can expect extreme shifts in weather patterns, ecology, and geology.

While the lasting effect of permafrost thaw on atmospheric carbon concentrations is uncertain, it is safe to say that the scale of the risk is potentially enormous and expensive into the trillions of dollars.

While methane from permafrost melt rises like a thick, invisible smoke stack, some members of the business world are focused on the economic potential of an increasingly iceless–and thus accessible–Arctic frontier.

The foremost reason for the Arctic’s economic promise is its massive oil and gas deposits.

The Arctic’s oil and gas fields account for 10.5 percent of global oil production and 25.5 percent of global gas production. And those numbers could jump soon. Initial estimates suggest that the Arctic may be home to an estimated 22 percent of the world’s undiscovered conventional oil and gas deposits, according to the U.S. Geological Survey.

Recent investments of many billions of dollars from oil giants–including Shell, ExxonMobil, ConocoPhillips, Statoil, Gazprom, and Rosneft–shows the excitement in the industry regarding the future revenues from these formerly ice-restricted resources.

An ice-free Arctic also creates shorter shipping routes.

For the first time ever, the Northern Sea Route, which passes through the Arctic to connect Europe to Eurasia, is open to commercial shipping, with over 70 vessels sailing through in 2013.

The Arctic also harbors valuable deposits of zinc, nickel, palladium, diamonds, platinum, cobalt, tungsten, uranium, and other minerals. And above ground, forestry, fishing, and many other industries promise to benefit from Arctic development.

A Dangerous Cycle

As melting ice unlocks the Arctic, it threatens to push temperatures to tipping points. It also unleashes economic activity that may spark positive feedback loops, bringing more and more Arctic melting – and thus more carbon dioxide and methane released from permafrost.

Additionally, as a warming climate allows snow and ice to thaw, tundra species are being replaced with evergreen trees, which absorb more sunlight. (Snow is white, so it absords less of the sun's heat than the darker evergreens.) That means that more tree cover will, counter-intuitively, further increase warming and thawing trends in the Arctic.

While the science regarding permafrost melt’s climate implications remains uncertain, the risk is so enormous that turning a blind eye while developing the Arctic frontier is tremendously irresponsible.

The ensuing hastening of permafrost’s melt could lead to global economic costs that drastically exceed the benefits from Arctic development.

Last week, the New York TimesDot Earth blog posted a sobering video of coastline erosion in Alaska. This is no simulation – it's a time-lapse video made from pictures taken two hours apart from late June to late July of this year.